"When asked about the children's documents, they had no documents," she said.

Social affairs minister Yves Christallin says the Americans are members of an Idaho-based charity called New Life Children's Refuge.

"This is an abduction, not an adoption," he said.

But the group's leader, Laura Silsby, says they were trying to take abandoned children to an orphanage across the border in the Dominican Republic.

"The entire team deeply fell in love with these children," she said.

"They are very, very precious kids that have lost their homes and their families and are so, so deeply in need of God's love and his compassion and just a very nurturing setting."

But a care centre chief says most of the children "have family" that survived the January 12 earthquake.

Patricia Vargas, regional director of the SOS Children's Village, where the children are being cared for, says officials at the Haitian Institute of Social Welfare told her "most of the kids have family".

Ms Vargas says older children of the group say some of the youngsters' "parents are alive, and some of them gave us an address and phone numbers".

The US embassy has confirmed 10 US citizens are being held for "alleged violations of Haitian laws related to immigration".

There have been growing concerns traffickers could try to exploit the chaos and turmoil following Haiti's quake to engage in illegal adoptions.

In addition to outright trafficking in children, authorities have voiced fears legitimate aid groups may have flown earthquake orphans out of the country for adoption before efforts to find their parents had been exhausted.